Question

What must occur for a change to be a chemical reaction?

Answer 1

Two conditions must be satisfied.........

Explanation:

`"(i) The formation of new substances........"`

`"(ii) And the making and breaking of strong chemical bonds............"`

And if both conditions are satisfied, then you have the specified `"chemical change."` There are many other answers here that classify common transformations, I urge you to seek them out........